Answer :
Answer:
Step-by-step explanation:
given that
A cereal manufacturer is concerned that the boxes of cereal not be under filled or overfilled.
Each box of cereal is supposed to contain 13 ounces of cereal.
A random sample of 31 boxes is tested.
The average weight is 12.58 ounces and the standard deviation is 0.25 ounces.
Sample mean = 12.58
Sample std deviation = 0.25
Sample size = 31
Sample std error = [tex]\sqrt{\frac{0.25}{\sqrt{31} } } \\=0.0449[/tex]
confidence interval can be calculated using t critical value because population sd is not known.
df = 30
t critical for two tailed = 1.697
Margin of error = [tex]1.697*0.0449\\=0.07620[/tex]
conidence interval = [tex](12.58-0.0762, 12.58+0.0762)\\=(12.5038, 12.6562)[/tex]
Since this does not contain 13 oz. we reject the claim that each box contains exactly 13 oz.